Changing a viewpoint (e.g., rotation or zoom) of a three-dimensional, image (e.g., a left-eye image and a right-eye image) changes a positional relationship in the depth direction between a plurality of objects included in the three-dimensional image or between portions of an object. As a result, for example, an object located on a far side is hidden by an object on a near side, reducing the visibility of the three-dimensional image.
In response, Patent Literature (PTL) 1 discloses a method for adjusting transparency of an object included in a three-dimensional image in accordance with a depth of the object. This can display an object located on a far side through an object located on a near side.
Moreover, PTL 2 discloses a method for maintaining stereoscopic effects by adjusting an amount of a disparity between a left-eye image and a right-eye image in accordance with a focal length upon zooming a three-dimensional image.